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Photoresponsive Liquid‐Crystalline Dendrimers Based on a Cyclotriphosphazene Core
Author(s) -
Jiménez Josefina,
Pintre Inmaculada,
Gascón Elena,
SánchezSomolinos Carlos,
Alcalá Rafael,
Cavero Emma,
Serrano José Luis,
Oriol Luis
Publication year - 2014
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201400190
Subject(s) - dendrimer , mesogen , azobenzene , materials science , photoisomerization , liquid crystal , polymer chemistry , lamellar structure , dispersity , chemistry , organic chemistry , polymer , isomerization , liquid crystalline , composite material , catalysis , optoelectronics
A series of new liquid‐crystalline dendrimers is synthesized from hexa(4‐hydroxyphenyloxy)cyclotriphosphazene as the central core and bis(MPA) as a branching agent. The dendrimers are functionalized with azobenzene mesogenic moieties. The monodisperse nature of the dendrimers is confirmed by 1 H and 31 P{ 1 H} NMR and by matrix assisted laser desorption/ionization (MALDI) mass spectrometry (MS). A study of the thermal properties reveals mesomorphic behavior. All of the materials exhibit a lamellar phase and this is confirmed to be smectic A in nature by X‐ray diffraction. A nematic phase is also observed for the dendrimers that contain 4‐cyanoazobenzene. A calamitic arrangement in which the mesogenic moieties point both upwards and downwards with respect to the cyclotriphosphazene core is proposed to explain the mesomorphic properties. The introduction of photochromic moieties leads to a photoresponse for these materials. The response to linearly polarized light is studied and an order parameter of about 0.5 is measured for dendrimer G1‐Azo‐3 .